Field of the Invention
The invention relates to an apparatus for joining flat electrical components of variable size, with the aid of a flexible film that contains electrical conductor tracks and an electrically conductive adhesive.
So-called heat sealing systems are known in which printed circuit boards and LCDs (liquid crystal displays) are joined together with the aid of polyester film, also known as flex film, that is coated with conductor tracks, and an electrically conductive adhesive (see the paper by Karl Lindner et al. of Weld-Equip, entitled "Pulse heat bonding a method for interconnections with Anisotropic Conductive Adhesive Foil (ACAF) and Heat Seal Connectors (HSC)", presented at the conference entitled "Adhesives in Electronics 94"). In such systems, the parts to be joined together, for instance an LCD component and a printed circuit board, are placed in a work piece receptacle together with the polyester film that is constructed as a flexible printed circuit board.
An anisotropic conductive adhesive is applied to peripheral regions of the LCD component and the printed circuit board that are to be joined to the polyester film. A die with a heatable sealing head is then moved from above onto joining points. The adhesive melts and electrically conductively joins the two joining partners to one another under pressure and heat. The conductive adhesive is constructed in such a way that only the conductor tracks of the respective joining partners that are located directly one above the other are electrically conductively joined.
In the known system, different heating or sealing heads are needed for various printed circuit board and LCD sizes, and those heads are each directed especially to one product. A new heating dye must be prepared for every other product, however minimally it may differ in dimensions from the previous ones. That change also necessitates an adaptation of a production program and a change in operating parameters in the mass production of products.
U.S. Pat. No. 5,468,315 discloses a device for producing multi-layered ceramic printed circuit boards, which has a workpiece receptacle for the workpieces to be joined, a die that can be pressed against the workpiece receptacle and is heatable, and resiliently supported peripheral elements disposed on both sides next to the workpiece receptacle.
Published Japanese Patent Application JP 7-65927 also discloses a device for thermocompression bonding that has a resiliently supported peripheral element.